The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions such as pacemakers, defibrillators, neuro-stimulators and therapeutic substance delivery pumps. Medical devices can be surgically implanted or connected externally to the patient receiving treatment. Clinicians use medical devices alone or in combination with therapeutic substance therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best and sometimes the only therapy to restore an individual to a more healthful condition and a fuller life. One type of medical device is an implantable drug pump used to treat conditions such as movement disorders, pain, and cancer and a wide variety of other medical conditions.
An implantable drug pump is defined herein as including any implantable therapeutic substance infusion device. An implantable drug pump is implanted by a clinician into a patient at a location appropriate for the therapy that interferes as little as practicable with patient activity. Typically, an infusion catheter is connected to the drug pump outlet and implanted to infuse the drug, infusate or other therapeutic substance at a programmed infusion rate and predetermined location to treat the medical condition. Reliable and accurate operation of the drug pump is important because both inadequate and unintended therapeutic substance infusion can create patient complications. In electrically powered implantable drug pumps, the period the drug pump can be implanted is often limited by factors such as battery consumption, corrosive damage, and mechanical wear. The relatively large size of some implantable drug pumps can limit locations where the device can be implanted in a patient. An example of an implantable drug pump is shown in the Medtronic, Inc. “SynchroMed® Infusion System” Product Brochure (1995).
Many drug pumps are configured, so the pump can be replenished with drug through the septum of a refill port while the pump is implanted, so the period the pump can be implanted may not be limited by drug capacity. This is commonly done by injecting a hypodermic needle through the skin and into the septum thereby providing access to refill the reservoir. In such devices a catheter access port is often provided in addition to the refill port. The catheter access port is also accessible percutaneously by hypodermic needle. Its septum provides direct access to the catheter bypassing the pump and allows a bolus of drug or fluid medication to be administered directly into the body at the site of the catheter. The catheter access port can also be used as a diagnostic tool to troubleshoot the catheter or infusion problems. An example of an implantable drug pump having a catheter access port is shown in U.S. Pat. No. 6,293,922 “Apparatus And Method For Guiding And Limiting Access By Hypodermic Needles To Septum Of A Human Implantable Medical Treatment Device” by Haase (Sep. 25, 2001).
Implantable drug pumps often require occasional access, usually with a needle, to replenish drug or inject drug into a catheter access port. To aid in the location of the hidden septum in an access port, palpation or a template can be used.
Use of a template can help avoid some of the common problems associated with accessing a hidden access port. For example, missing the port will require the patient endure multiple needle sticks. A template can minimize the need to use radiological instruments to guide the clinician's insertion of a needle into an access port. Additionally, hitting the surface of the device can cause the sharp (but thin) point of the needle to bend, causing a burr that will make the subsequent needle stick more painful, or cause the clinician to get another needle. If the clinician is fooled into thinking they have accessed the device, she can inject the drug into the pocket, causing delivery to the wrong site in the body. Finally, the clinician can access the wrong port in the implantable device, which can have unexpected consequences. Examples of templates for implantable drug pumps as disclosed in the Medtronic Model 8551 Refill Kits and Model 8540 Catheter Access Port Kit and Pfizer Infusaid Implantable Drug Deliver System shown in the Clinician's Manual for The Infusaid Constant Flow Implantable Pump (Model 400) (1992).